Recently, along with a demand for reduction in cost and the downsizing of electronic equipment, a miniaturized power MOSFET has been requested. As such a power MOSFET, a power MOSFET 900 shown in FIG. 17 is considered where source electrodes 934 and a source region 924 are electrically connected to each other through metal plugs 930 (for example, see patent literature 1 with respect to a semiconductor device using metal plugs).
A power MOSFET 900 according to Background Art is a power semiconductor device which has a super junction structure formed of an n−-type column region 913 and a p−-type column region 915 which are alternately arranged, and defines: an active element part R1 which is a region where a source electrode 934 is formed as viewed from an upper surface side which is a front surface side of the n−-type column region 913 and the p−-type column region 915 (hereinafter also simply referred to as an upper surface side); and a gate pad part R2 which is a region where a gate pad electrode 935 is formed as viewed from the upper surface side.
The active element part R1 includes: an n+-type low-resistance semiconductor layer 912; a plurality of n−-type column regions 913 arranged at a predetermined interval along a predetermined direction; a plurality of p−-type column regions 915 arranged alternately with the n−-type column regions 913 along the predetermined direction; a p-type base region 916 formed on a front surface of the n−-type column region 913 and a front surface of the p−-type column region 915; a trench 918 formed in a region where the n−-type column region 913 exists as viewed from the upper surface side, and is formed up to a depth position where the trench 918 penetrates the base region 916 and reaches the n−-type column region 913; a gate insulation film 920 formed on an inner peripheral surface of the trench 918; a gate electrode 922 buried in the trench 918 by way of the gate insulation film 920; an n+-type source region 924 formed such that the source region 924 is disposed on a front surface of the base region 916, and at least a portion of the source region 924 is exposed on the inner peripheral surface of the trench 918; an interlayer insulation film 926 configured to cover at least the source region 924, the gate insulation film 920 and the gate electrode 922; a contact hole 928 formed in a region where the p−-type column region 915 exists as viewed from the upper surface side, and penetrates the interlayer insulation film 926 and reaches at least the base region 916; a metal plug 930 formed by filling predetermined metal in the contact hole 928; a p+-type diffusion region 932 formed so as to be in contact with a bottom surface of the metal plug 930 and having higher dopant concentration than the base region 916; the source electrode 934 formed on the interlayer insulation film 926, and electrically connected to the base region 916, the source region 924 and the p+-type diffusion region 932 through the metal plug 930; and a drain electrode 936 formed on a front surface of the low-resistance semiconductor layer 912.
The gate pad part R2 includes: the low-resistance semiconductor layer 912; the n−-type column region 913; the p−-type column region 915; the base region 916; the interlayer insulation film 926; the gate pad electrode 935 formed on the interlayer insulation film 926; and the drain electrode 936 formed on the low-resistance semiconductor layer 912 (for example, see patent literature 2 with respect to a power semiconductor device which has a super junction structure and in which the active element part and the gate pad part are defined).
The power MOSFET 900 according to Background Art includes the metal plug 930 and hence, unlike a power semiconductor device where the source electrode and the source region are brought into direct contact with each other, it is unnecessary to form a contact hole having a large diameter and hence, it is possible to provide a miniaturized power MOSFET. As a result, it is possible to provide a power MOSFET which can satisfy a demand for both reduction in cost and downsizing of electronic equipment.
Further, the power MOSFET 900 has the super junction structure formed of the n−-type column region 913 and the p−-type column region 915 which are alternately arranged. Accordingly, it is possible to lower ON resistance while maintaining a high withstand voltage.